Field of the Invention
The present invention relates to an inkjet-type print apparatus which suppresses drying of nozzles by supplying humidified gas.
Description of the Related Art
In a general inkjet print apparatus, if nozzles are not driven for a long period of time, defective ejection occurs due to thickening caused by evaporation of solvent (moisture) of ink in the nozzles. To avoid this problem, a method for supplying high-humidity gas to portions near the nozzles is employed.
Japanese Patent Laid-Open No. 2011-235468 discloses a configuration in which humidified gas is supplied from an upstream of a plurality of arranged print heads so that the humidified gas flows to gaps between the print heads and a sheet (print gaps) along a direction in which the sheet is conveyed.
In this configuration, the humidified gas is successively supplied to the print gaps of the individual print heads which are arranged along the sheet conveyance direction. Therefore, a long period of time is required until the humidified gas reaches a downstream side. Furthermore, to supply the humidified gas to the narrow print gaps having a large flow resistance in a short time, a high supply pressure of a supply unit which supplies the humidified gas is required. Furthermore, to obtain the high supply pressure, the supply unit which supplies the humidified gas is required to have high power, and accordingly, the size of an apparatus is increased and noise is increased. In addition, a speed of airflow is increased in the narrow print gaps, and accordingly, ejection of ink from the heads may be deviated.
On the other hand, in an example illustrated in FIG. 17 of Japanese Patent Laid-Open No. 2005-271314, humidified gas is supplied from a side to a certain space between adjacent two of a plurality of aligned print heads. The supplied humidified gas passes through one of the gaps between the print heads and a sheet (print gaps) to a next space so as to be discharged from the certain space. In both of the disclosures, humidified gas is supplied to print gaps so that nozzles are prevented from being dried.
In the configuration in Japanese Patent Laid-Open No. 2005-271314, since the humidified gas supplied from the side to the certain space is supplied through a narrow print gap to the next space, a long period of time is required until the humidified gas spreads. Furthermore, a high supply pressure of the humidified gas is required. Moreover, two ducts, that is, a supply duct and a discharge duct, are disposed in one space positioned between adjacent print heads, and accordingly, a large channel cross-section area may not be ensured resulting in increase of a channel resistance. This also causes increase of the supply pressure of the humidified gas. That is, the configuration in Japanese Patent Laid-Open No. 2005-271314 also has a problem the same as that of the configuration in Japanese Patent Laid-Open No. 2011-235468.
The present invention provides a print apparatus which suppresses drying of nozzles by supplying humidified gas in a short time without increasing a supply pressure.